title: Multifunctional weaponry: the chemical defenses of earwigs.
abstract: Earwigs protect themselves against predators using pincer-like cerci and/or malodorous exudates secreted from abdominal glands. Little is known about the chemistry of these secretions and their potential functions. However, because earwigs live in aggregations and overwinter in soil, they are exposed to high microbial loads throughout their lifecycle, and we therefore hypothesized that the secretions are used not only to deter predators but also to combat pathogens and parasites in their environment. We analyzed the defensive secretions of the European earwig Forficula auricularia, the short-winged earwig Apterygida media and the woodland earwig Chelidurella guentheri by gas chromatography-mass spectrometry. The secretions of all three species contained 2-methyl-1,4-benzoquinone and 2-ethyl-1,4-benzoquinone, whereas A. media also produced 2,3-dimethyl-1,4-benzoquinone and 2-ethyl-3-methyl-1,4-benzoquinone. The latter has not been identified in the exudates of insects before. The composition and/or quantity of these components were species-specific and partially sex-specific. All secretions showed antimicrobial activity against Gram-positive and Gram-negative bacteria as well as two entomopathogenic fungi. Furthermore, the secretion of F. auricularia displayed nematicidal activity against Caenorhabditis elegans. Our data support the hypothesis that earwig secretions are multifunctional, serving both to deter predators and sanitize the microenvironment.
authors.affiliation: Institute of Phytopathology and Applied Zoology, Justus Liebig University Giessen, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Electronic address: tina.gasch@agrar.uni-giessen.de.
authors.forename: Tina
authors.initials: T
authors.lastname: Gasch
authors.forename: Matthias
authors.initials: M
authors.lastname: Schott
authors.forename: Christoph
authors.initials: C
authors.lastname: Wehrenfennig
authors.forename: Rolf-Alexander
authors.initials: RA
authors.lastname: Düring
authors.forename: Andreas
authors.initials: A
authors.lastname: Vilcinskas
mesh_terms: D000819:Animal Communication; D000818:Animals; D000890:Anti-Infective Agents / Q000032:analysis*; D012634:Bodily Secretions / Q000737:chemistry*; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D007313:Insecta / Q000502:physiology*; D008297:Male
chemical_list: D000890:Anti-Infective Agents
keywords: 1,4-Benzoquinones; Antimicrobials; Chemical ecology; Defensive secretion; Dermaptera; Nematodes